"Today, I called Dr. Ruiz and congratulated him on his impressive victory. Dr. Ruiz will do a fine job if he is guided as well by the people of the congressional district as I was. Please give him the opportunity to succeed," Bono Mack said in a statement.

Ruiz said he thanked Bono Mack for her dedicated public service when the two spoke Friday, and he assured voters that he would strive to represent everyone in the district, no matter their party affiliation.

"I believe that this election sends a message that it's time to put an end to partisan gridlock," Ruiz said. "I'm excited to go to Washington and represent the entire district — including supporters of Congresswoman Bono Mack. The issues that we have to work on are clear: the high cost of healthcare, bringing jobs to the Coachella Valley, and investing in education and renewable energy."

Bono Mack fought the toughest battle of her 14-year political career, which began when she was elected to replace her husband, singer Sonny Bono, after his death in a skiing accident.

California's revised political districts, combined with a decline in GOP voter registration, turned the contest into a high-stakes tossup. The split between Republicans and Democrats in the district — which includes Palm Springs, Indio and Blythe — is less than 1 percentage point.

During the campaign, Bono Mack accused Ruiz of being a "radical" for taking part in a Native American protest of Thanksgiving when he was a Harvard medical student in the late 1990s.